13. Unlike the Greeks, the Romans often used more than one order of columns in tiered arcades. Which order was almost invariably the base?
From Quiz Orders of Architecture
Answer:
Doric
The Romans codified the orders, and also developed square columns, called pilasters, and half-columns, attached to a wall. They established regular proportions for the different orders, and appropriate spacings between columns. Where multiple columns were required, they were arranged with the simplest (Doric, or in the Renaissance, Tuscan) at the bottom, then through Ionic and Corinthian to the most dramatic, Composite order on the top storey.